New Words：

silent [ˈsaɪlənt] adj.不说话的；沉默的

Sample Sentences：

He remained silent from first to last.
He was silent for a moment, then began his answer.
He spoke no English and was completely silent during the visit.

New Words：

population [ˌpɒpjuˈleɪʃn] n. 人口，人口数量

Sample Sentences：

What is the population of your country?
Japan has a population of nearly 130 million.
The entire population of the town was at the meeting.

New Words：

several [ˈsevrəl] pron. 几个;数个;一些

Sample Sentences：

He's written several books about India.
He will have to stay in hospital for several days.
Several of the paintings were destroyed in the fire.

New Words：

prove [pruːv] v. 证明;证实

Sample Sentences：

I'll prove to the world that he was right.
Just give me a chance and I'll prove it to you.
I can prove to you that he is not telling the truth.

New Words：

require [rɪˈkwaɪər] v. 要求;需要

Sample Sentences：

The roof requires repairing.
I require a seat by the Window.
All passengers are required to show their tickets.